This invention relates to rapid-acting fire suppressant valves that utilize rupturable diaphragms to control outflow of pressurized suppressant from thick-walled containers (bottles). Valves of this general type are shown in U.S. Pat. No. 3,491,783 to O. Linsalato, U.S. Pat. No. 3,762,479 to L. Fike et al., and U.S. Pat. No. 3,915,237 to E. Ronzniecki (the present inventor). General objects of my present invention are to provide a rupturable diaphragm valve that has a fast response time, that has a large flow area, that is of leak-free character during standby periods, and that includes means for trapping flames and combustion products generated by a squib actuator used to rupture the diaphragm. A particular object is to provide mechanism for safely handling diaphragm fragments that could produce personnel injuries if allowed to flow with the fire suppressant jet stream. In my design both the squib-actuator flame and diaphragm fragments are kept out of the suppressant jet stream path.